Numerous types of hearing aids are known and have been developed to assist individuals with hearing loss. Examples of hearing aid types currently available include behind the ear (BTE), in the ear (ITE), in the canal (ITC), and completely in the canal (CIC) hearing aids. In many situations, however, hearing impaired individuals may require a hearing solution beyond that which can be provided by such a hearing aid using an internal microphone alone. For example, hearing impaired individuals often have great difficulty carrying on normal conversations in noisy environments, such as parties, meetings, sporting events, etc., involving a high level of background noise. In addition, hearing impaired individuals also often have difficulty listening to audio sources located at a distance from the individual or to several audio sources located at various distances from the individual and at various positions relative to the individual.
The characteristics and location of a hearing aid internal microphone often results in excessive pickup of ambient acoustical noise. In the past, this has often been overcome by the direct magnetic coupling of a speech signal into a telecoil, which is often incorporated internally in hearing aids. The telecoil's original purpose was to pick up the stray magnetic field from conventional telephone receivers, which often, although not always, had sufficient strength for efficient direct coupling of the telephone signal. The telecoil's use has expanded to use a receiver in “room loop” systems, where a large room is “looped” with sufficient audio signal-driven cabling to create a reasonably uniform, generally vertically oriented magnetic field within the room. The telecoil has also been used to receive magnetically coupled audio signals from special “neck loops” and thin “silhouette” style “tele-couplers” that fit behind the ear, next to a BTE aid.
A common problem with prior art tele-couplers of the neck loop and silhouette styles has been the difficulty of bathing the telecoil in a magnetic field that is both of sufficient strength and sufficient uniformity in relation to typical relative tele-coupler/telecoil positionings to ensure a predictable, consistent audio coupling at a volume level adequate for comfortable use and that can consistently overcome environmental magnetic noise interference. Additionally, silhouette style tele-couplers, which are generally designed with BTE aids in mind, have not successfully achieved sufficient field strength at the greater distances needed to reach the ITE telecoils, or provided an appropriate field orientation for optimum coupling.
Further, the net frequency response obtained with prior art tele-coupler/telecoil systems has been uncontrolled, unpredictable, and not generally uniform. The combination of the non-uniform frequency characteristics of the field produced by the typical transmitting inductor and the non-uniform frequency response of the typical receiving telecoil results in unsatisfactory overall frequency response for the user.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with aspects of the present invention as set forth in the remainder of the present application and with reference to the drawings.